Annealing atmosphere-dependent electrical characteristics and bias stability of N-doped InZnSnO thin film transistors

Abstract

The dependence of electrical characteristics and gate bias stress stability of N-doped InZnSnO (IZTO:N) thin film transistors (TFTs) on annealing atmosphere was investigated. The annealing process was performed in air, O2 and N2, respectively, after the deposition of IZTO:N thin film by magnetron sputtering. All annealed IZTO:N films are amorphous and show a high transmittance in the visible light range. The N2-annealed TFT has the highest saturation mobility (μSAT) of 39.5 cm2 V−1s−1 and the lowest subthreshold swing (SS) of 0.40 V/decade. The air-annealed TFT shows similar mobility and SS to the N2-annealed TFT while the O2-annealed TFT shows the lowest mobility and the largest SS. We found that annealing atmosphere has impact on the bias stress stability of the TFTs. Bias stress induced threshold voltage shift of the O2-annealed TFTs is reduced compared to that of air-annealed and N2-annealed TFTs due to the decrease in oxygen vacancy.